Renewable Energy Sources (RES) such as wind and solar power are increasing rapidly in the world. In small grids with high RES penetration, such as on islands, the fast intermittent fluctuations of RES put a challenge to conventional regulation units such as thermal plants and gas generators.
With increasing amounts of RES in the power grids and with growing sizes of the renewable power plants, regulators and Transmission System Operators (TSOs) are implementing new grid codes that put constraints on maximum active power ramp rates.
System integrators have started to install Battery Energy Storage Systems (BESS) to meet these constraints.
A standard ramp rate control method for controlling a BESS does not require any forecast of the RES power output, but ramp rate control methods exist which use forecasting.
U.S. Pat. No. 8,295,989 discloses controlling ramp-down rate in response to a prediction of an overly rapid reduction in system output. In this procedure, a ramp-down rate that would otherwise exceed the rate of change tolerable by the grid can be kept within tolerable limits if the power loss is predicted in advance.
US 2010/198420 discloses tracking movement of clouds is used to predict the effects of cloud cover on irradiation of a solar-powered distributed power generation system. The predictions enable a solar power plant to maintain the changes in its total power output within operating requirements with less or no dependence on energy storage.